Certain cannulas have surgical tools located within the cannula for performing surgical operations on a vessel of interest. The cannula is inserted into a surgical site with the distal end of the cannula positioned near the vessel of interest. An endoscope positioned within the cannula allows the surgeon to view the target area, and allows the surgeon to position the surgical tool correctly.
However, the surgical tool may be inadequate to safely and effectively perform its operation. For example, if the target vessel is a side branch or tributary of a vein such as a saphenous vein, the surgical tool may sever or damage the vein while being used to cut the side branch. Thus, there is needed a cannula which is able to isolate the target vessel of interest to allow the surgical tool to perform safely and effectively.